In the face of limited microwave frequency spectrum and radio's susceptibility to fading fiber optic or light wave technology is rapidly becoming the preferred method of digital transmission. Fiber optics overcome the disadvantages of microwave radio. It is inexpensive to manufacture, has vast bandwidth, is not susceptible to interference and fading, and communications can be conducted over a fiber optic system with almost complete assurance of privacy. Fiber optic cable is an important replacement for twisted pair cable because of its greater capacity and smaller physical diameter. On the other hand optical cable requires special tools and techniques for installation. The fibers must be carefully aligned into fixtures for either termination or splicing and requires special apparatus.
The presently used method for splicing fiber optic cable involves the use of a specially equipped truck. In a typical situation for installing aerial cables the cable is suspended from conventional poles and their supporting strands while leaving 50 feet or more of coiled cable at each pole at which a splice is to be constructed. This slack cable is then brought down into a splice truck or trailer. The splice is formed in the truck or trailer using a conventional splicing device and the cable is then suspended from the pole and strand. The suspended cable splice has coils at both sides thereof as required by the cable slack which permits the cable to be lowered into the truck.
Fiber cable splices are usually created either through a fusion process or the use of mechanical connectors. Each method has its advantages and disadvantages but it appears that the fusion method is evolving as the preferred method in view of the superior quality splice which results. Fusion splicers initially were very sensitive to environmental conditions which led to the use of an enclosed truck or trailer to provide the optimum portable environment. The trucks or trailers generally were insulated and air conditioned so that the loop could be uncoiled, run into the truck, sealed off and then manipulated on a well lit work bench. Originally the work bench and/or the truck or trailer required leveling to provide a stable, stationary, and level work surface.
Pursuant to that method the fibers were arranged in each end of the splice device, aligned under a microscope, and fusion performed. Subsequently some degree of automation was added and the splicing sets became less sensitive to atmospheric conditions. Humidity was originally a critical factor because of the use of an electric arc to create the heat necessary to melt the glass and improper atmospheric conditions could cause the arc to misfire or the creation of a poor fuse.
Currently available splice sets are much less sensitive to environmental conditions and are more automated. The microscope eye-piece has been eliminated in favor of a small video screen for making and checking alignments. Despite the foregoing, current fiber optic cable splicing still requires a significant amount of hand work and continues to require an extremely steady work surface. The cladding is still removed by hand and the individual fibers must be manually placed into a jig on both sides in order to permit the splice set to accomplish the necessary alignment. In the case of a loose tube cable, multiple fibers are removed from a tube and manually configured into a flat ribbon. They are then cut, cleaved, cleaned and inserted into the set to permit it to perform its process. One advantage of the current procedure is that it has made feasible the formation of fusion splices in an unconditioned environment.
Fiber optic cable splicing originally was performed on trunk cables so that the splices were spaced at 4-6,000 foot intervals. Current practice is to build distribution plants which involve terminals on every second, third or fourth pole and branch cable splices at frequent intervals very similar to the copper environment. The frequency of splicing is significantly greater than in the trunk only situation. Using the old splice technique this involves leaving coils of cable on every second or third pole in densely populated environments. Such a procedure is not only aesthetically objectionable but also relatively costly in view of the comparatively higher cost of fiber cable as compared to copper. Still further, productivity is poor in that it can require 15 minutes to half an hour to coil and store the slack once the splice is completed.
The initial approach to alleviating these problems involved attempting to splice in the air. Relying on conventional equipment the first approach was the use of a truck supported bucket or cherry picker with a work platform built or mounted onto the bucket. This proved unsatisfactory as it was found that the bucket constitutes a very unstable platform for work which is so sensitive to movement. The bucket is suspended from the vehicle chassis by suspension arms which inherently are subject to significant flexure. In addition it was found that unacceptable bucket movement could be caused by a slight amount of body movement by the operator. This tended to pull the fibers from the jigs and require rearrangement.
The next thought was to attempt to steady the bucket by attaching it to the strand or to a pole to provide a stable platform. However this would create a violation of accepted safety practices. The next approach was a revisiting of the use of the old wooden splicer's platforms that formerly were hung from the strand. However, the same type of problems were encountered. Every movement of the operator brings a resultant movement of the platform.
While platforms have been previously mounted on or suspended from telephone or power poles to permit work on equipment, these have conventionally constituted body support platforms to permit a worker on the platform to work on pole supported equipment. One typical pole platform of this type is illustrated in U.S. Pat. No. 2,168,111 issued Aug. 1, 1939 to R. C. Barnes. That patent shows a platform covered by a rubber pad mounted on a wooden pole through the use of burrs, a clamping chain, and a diagonal brace terminating in a "V" shaped pole engaging member for securement thereto by spurs or burrs. An alternate electrically insulated aerial platform for use by a lineman on utility poles is illustrated in U.S. Pat. No. 4,641,727 issued Feb. 10, 1987, to Marvin D. McKelvy. In that patent the platform presents a substantially flat upper surface where a lineman may stand, sit, or kneel and is provided with a railing assembly extending upwardly from the platform and terminating in a ring adapted to be connected to a lineman's safety belt. The platform is attached to the pole by insulating members so that the lineman on the platform is insulated from electrical connection to the pole.
A simpler version of a workman's platform for use by lineman in work on poles is shown in U.S. Pat. No. 783,837, issued Feb. 28, 1905, to R. G. Johnston. Another type of workman-supporting pole mounted platform is illustrated in U.S. Pat. No. 3,776,498 issued Dec. 4, 1973, to Allen Peters, et al. In that patent there is shown a bracket for supporting scaffolding from a pole structure such as a pier or piling.
In addition to the foregoing it is common knowledge that there are available numerous forms of portable tree stands for use by hunters. Illustrative examples of such stands are found in U.S. Pat. No. 4,730,700 issued Mar. 15, 1988, to Miller et al.; U.S. Pat. No. 1,206,574 issued Nov. 28, 1916, to F. Miller; U.S. Pat. No. 3,990,537 issued Nov. 9, 1976 to Gordon G. Swenson et al.; and U.S. Pat. No. 4,427,092 issued Jan. 24, 1984, to Lynn A. Tentler.